Hello,
We have a problem with SFP+ fiber links between one CRS326 that is connected to two CRS312 switches using 10 Gbps fiber. The fiber interface occasionally goes down and back again after 1s.
Logs on CRS312 are like this (combo4 has SFP+ module):
Oct/13/2020 14:19:45 interface,info combo4 link down
Oct/13/2020 14:19:46 interface,info combo4 link up (speed 10G, full duplex)
Oct/13/2020 14:44:16 interface,info combo4 link down
Oct/13/2020 14:44:17 interface,info combo4 link up (speed 10G, full duplex)
Oct/13/2020 15:49:32 interface,info combo4 link down
Oct/13/2020 15:49:33 interface,info combo4 link up (speed 10G, full duplex)
CRS326 logs sometimes show link down/up, sometimes they don’t. It’s the same for the SFP+ link between CRS326 and the other CRS312. The problem only exists when interface is in auto-negotiation mode (default). If I turn it off and manually select 1G on both sides, the link is stable with no disconnects indicated in the log files. However, we want a stable 10 Gbps connection. SFP+ modules are Mikrotik S+31DLC10D, all cables are SM and all 3 switches use RouterOS 6.47.4 with the latest firmware.
We have tried the following with no change: Replaced fiber cables, connected switches directly with short fiber patch cables, replaced all 4 SFP+ modules and replaced CRS326 with a new one.
We have never tried connecting the two CRS312 together using SFP+ (they are connected using 2 copper interfaces in a bond), nor replacing one.
Does any one of you have any idea what could be the problem? I’ve already asked Mikrotik support and gave them supout.rif and log files, but they take 2-3 days to respond each time I reply to them and we’re running out of time.